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Topic: Ask the Experts: John Palmer (Read 22586 times)

John Palmer is the author of How to Brew and the co-author of Brewing Classic Styles with his good friend Jamil Zainasheff. Together they co-host the popular brewing podcast, Brewstrong. John is a regular on the international homebrewing competition circuit, having been invited to speak and judge at conferences and competitions in such diverse locations as Australia, Argentina, North Dakota, and Kansas, and Orlando. John has been brewing for nearly 20 years, and has frequently underwhelmed his compadres in the Crown of the Valley Brewing Society with his brewing frequency and colorful witticisms to “brew as I say, not as I do.”

John is a metallurgical engineer by trade and has particularly applied himself to understanding the processes of brewing from an engineering point of view, including malting, mashing, water chemistry, lautering, clarity, color, and foam retention. In 2007, John was deeply honored with an AHA Governing Committee Recognition Award for Outstanding Service.

Bill from Ontario asks:John, in How to Brew you seem to recommend a somewhat thinner mash (1.5 – 2.0 quarts of water per pound of grain) than has been used traditionally by most homebrewers (typically 1.2 – 1.4 quarts per pound). Are there benefits of a thinner mash that cause you to recommend this? And when designing a new mash tun, do you recommend a larger size to allow room for the greater volume of water a thinner mash requires?

Palmer answers:This turned out to be a difficult question to answer in terms of hard facts. The recommendation flows from two sources. First, a review of professional brewing journals shows that grist ratios of 1.5-2.5 quarts per pound (3-5 liters/kg) are common, and are even cited as being standard by brewing textbooks like the Technology of Malting and Brewing by Wolfgang Kunze, and Briggs et al., in Malting and Brewing Science. Why do they commonly use these higher ratios? Probably initially because it made pumping the mash easier, but the fringe benefits have been substantiated. Kunze states that higher ratios are used to preserve the color and fermentability of pale beers while lower ratios are used for darker beers to gain more aroma and complexity of flavor. Malting and Brewing Science cites Harris (1962) stating that ratios of 1.5-3 quarts per lb (3-6 L/kg) generally favor maximum fermentability, while maximum yield is obtained at 1.25 quarts per lb (2.5 L/kg). However, these effects are a distant second to the effect of mash temperature.

My second reason is that I had noted from my own experimentation that multiple infusion mashes (or step mashing with multiple infusions if you prefer) often resulted in grist ratios of near 3 quarts per lb, and that I had no problems with the conversion of the mash. After discovering that the professionals accepted higher ratios as well, I promoted them for being useful to homebrewing techniques like multiple infusion mashing. The only downside is the total volume of the mash as you noted. So, yes, I recommend planning for a larger mashing vessel. I often use a 15 gallon pot for mashing a five gallon batch.

Dylan from Pennsylvania asks:Your book, How to Brew, is one of the most widely used resources for introductory brewing knowledge and troubleshooting brewing/fermation/finished beer issues.

What issues have you struggled with in your own brewing and where do you turn for more info or assistance?

Palmer answers:What issues have I struggled with? Primarily indecision and lack of credible references! Whenever I have a question about brewing, I try to drill down to the most basic reason Why?, and build the answer from there. I routinely turn to the other homebrewing texts to look for answers (Papazian, Daniels, Mosher, Miller, etc). If the question is more technical, I look it up in Kunze’s Technology of Brewing and Malting, or Malting and Brewing Science by Briggs et al., or Brewing by Lewis and Young. If the question is really cutting edge, then I will turn to the professional brewing journals of the American Society of Brewing Chemists and the Master Brewers Association of the Americas. I am a member of both and being able to search the abstracts is a goldmine. If I can’t find the answer anywhere, I turn to friends who have focused on that subject. I remember trying to find the gelatinization temperature range of wheat and rye when I was writing the book and contacted a friend in Australia, who put me in touch with a friend of his in Finland, whom was able to find the answer in a book on Cereal Science and Technology. Brewers are very helpful people worldwide.

Jeff from Tennesse asks:John, thanks for the great info over the years. This is Jeff. I have been an ale brewer for the past few years but now have a spare fridge to lager in. My first attempt followed the guidelines in Brewing Classic Styles to the tee. The pilsner I brewed came out undrinkably rotten egg like and butter popcorny. I lagered for 4 weeks then carbed in kegerator hoping conditioning would help. Still undrinkable. I now have it out in the basement which is 67 degrees and I shook up the corny hoping to get whatever yeast that are left into solution to consume the diacetyl. Saflager dry yeast was used, s-23. Thanks in advance for any recommendations.

Palmer answers:Those two symptoms indicate that the fermentation was not complete. The rotten egg sulfur smell means that the fermentation was not vigorous enough for the CO2 to scrub the sulfur compounds out of the beer, and the buttery popcorn is a sure sign of diacetyl, which means that the yeast pooped out or were chilled into hibernation before conditioning was complete.

Some lager yeasts throw more sulfur than others, but the sulfur compounds originate in the malt. A longer boil will help reduce the sulfur in the wort, and a larger pitching rate or a warmer fermentation generally will produce a more vigorous fermentation to scrub those compounds out. The high diacetyl can be controlled by pitching fresher yeast, and ensuring that the yeast are not stressed when they hit the wort. The use of liquid versus dry yeast does not guarantee better beer, but if a liquid yeast is used, and was pitched to a starter before pitching to the wort, then that yeast will be healthier and have better vitality than dry yeast that was simply re-hydrated. Your message doesn’t say, but I suspect that a combination of yeast packet age, lack of a starter, and cooler than optimum fermentation temperatures contributed to your problem. To clean up the diacetyl, you should pitch a starter at high krausen for best results.

Sal from California asks:Well, I guess all questions are allowed and I beg your pardon if this one is too basic. It is, however, a nagging problem for which I have long searched for an answer. I have multiple times attempted to add fruit juice, purée or paste to my brews, but the result is always disappointing - and often absolutely undrinkable. Last weekend I dumped a whole batch of dry stout - to which I had added homemade peach purée - down the drain. It was terrible.

My "beers with fruit-derivate addition" acquire a bitter, "woody" taste that only gets worse with time. The phenomenon seems to be more pronounced with the increase of solid content - i.e., it worse with fruit purée than fruit paste, and worse with fruit paste than fruit juice.

I thought the problem was due to contamination with bacteria or wild yeast - even though there was no evidence of it whatsoever - but that does not seem to be the case, as I've attempted several pasteurization techniques (and temperature ranges/patterns) but can't notice any improvement at all... Changing the "moment" of addition of fruit product from one brewing step to another (say, primary fermentation, early secondary fermentation, late secondary fermentation) does not impact the (poor) results significantly either.

Curiously, I have no problem adding "non-fruit vegetable products" to beers. I've added carrot purée to an experimental batch and the result was not bad at all - but if I add banana paste or something alike, well, it's a whole different - and much less pleasant - story.

Final words: the problem seems to be worse with less acidic fruits. Maybe these issues have indeed biologic origin and the citric acid in these fruits is dampening the problem??? Oh well...

Thanks a lot for sharing you expertise, John. And congrats to the AHA for this initiative - pretty cool indeed.

Palmer answers:This is an interesting question that could have several possible causes. The key clue though is that it gets worse with time. It could be contamination by Brettanomyces or Pediococcus, although those are not typically described as bitter and woody. Those flavors can be an aspect, but I wouldn’t expect them to be the dominant description, and I suspect you would be describing phenolic aromas and flavors as well if infection were the case.

I have a feeling your problem is oxidation and staling of the lipids and fatty acids from the fruit. It makes sense that the less acidic fruits would tend to have more alkaline oxidation compounds and therefore taste more bitter. Mold may also be a factor, and again, a less acidic wort would be more likely to develop mold. I recommend that you talk to someone that makes wine at your local brewshop; they will probably be much more familiar with this type of off-flavor since it seems to be fruit-related. I have never studied wine myself, but I bet it would be helpful in this case.

Tom from Michigan asks:I have a few questions about secondary fermentations. I've read both pros and cons for 2nd fermentations and it is driving me crazy what to do. One, are they necessary for lower Gravity beers?

Two, what is the dividing line between low gravity and high gravity beers? Is it 1.060 and higher?

Three, I have an American Brown Ale in the primary right now, a SG of 1.058, Should I secondary ferment this or not?

Your advice is appreciated, thanks for all you do!

Allen from New York asks:John, please talk about why or why not you would NOT use a secondary fermenter (bright tank?) and why or why not a primary only fermentation is a good idea. In other words, give some clarification or reason why primary only is fine, versus the old theory of primary then secondary normal gravity ale fermentations.

Palmer answers:These are good questions – When and why would you need to use a secondary fermenter? First some background – I used to recommend racking a beer to a secondary fermenter. My recommendation was based on the premise that (20 years ago) larger (higher gravity) beers took longer to ferment completely, and that getting the beer off the yeast reduced the risk of yeast autolysis (ie., meaty or rubbery off-flavors) and it allowed more time for flocculation and clarification, reducing the amount of yeast and trub carryover to the bottle. Twenty years ago, a homebrewed beer typically had better flavor, or perhaps less risk of off-flavors, if it was racked off the trub and clarified before bottling. Today that is not the case.

The risk inherent to any beer transfer, whether it is fermenter-to-fermenter or fermenter-to-bottles, is oxidation and staling. Any oxygen exposure after fermentation will lead to staling, and the more exposure, and the warmer the storage temperature, the faster the beer will go stale.

Racking to a secondary fermenter used to be recommended because staling was simply a fact of life – like death and taxes. But the risk of autolysis was real and worth avoiding – like cholera. In other words, you know you are going to die eventually, but death by cholera is worth avoiding.

But then modern medicine appeared, or in our case, better yeast and better yeast-handling information. Suddenly, death by autolysis is rare for a beer because of two factors: the freshness and health of the yeast being pitched has drastically improved, and proper pitching rates are better understood. The yeast no longer drop dead and burst like Mr. Creosote from Monty Python’s The Meaning of Life when fermentation is complete – they are able to hibernate and wait for the next fermentation to come around. The beer has time to clarify in the primary fermenter without generating off-flavors. With autolysis no longer a concern, staling becomes the main problem. The shelf life of a beer can be greatly enhanced by avoiding oxygen exposure and storing the beer cold (after it has had time to carbonate).

Therefore I, and Jamil and White Labs and Wyeast Labs, do not recommend racking to a secondary fermenter for ANY ale, except when conducting an actual second fermentation, such as adding fruit or souring. Racking to prevent autolysis is not necessary, and therefore the risk of oxidation is completely avoidable. Even lagers do not require racking to a second fermenter before lagering. With the right pitching rate, using fresh healthy yeast, and proper aeration of the wort prior to pitching, the fermentation of the beer will be complete within 3-8 days (bigger = longer). This time period includes the secondary or conditioning phase of fermentation when the yeast clean up acetaldehyde and diacetyl. The real purpose of lagering a beer is to use the colder temperatures to encourage the yeast to flocculate and promote the precipitation and sedimentation of microparticles and haze.

So, the new rule of thumb: don’t rack a beer to a secondary, ever, unless you are going to conduct a secondary fermentation.

Liam from Ohio asks:I seem to lose my hop flavor in the final product?? no matter how much I put it. gravities are in the 60's, fresh, med carbonation? How much grain for a boil or where to find formula? They always write about O2 but never say how many liters for how long? Sorry for the three questions but these always come and thank you.

Palmer answers:Hop flavor and bitterness will fade due to oxidation, so that may be your problem. The oxidation product of isomerized alpha acid is not bitter, and will fade with time, depending on the amount of oxygen present in the package and the temperature (warmer = faster). It could also be your hop source – if the hops are old or stored poorly before you buy them, then there will be a lot less bitterness going into your beer than you are calculating. It’s hard to say without knowing more about your ingredients and process.

How much grain for a boil? Do you mean how much grain or grist to boil for a decoction step? That information is in the current edition of How To Brew on pages 172-173. Basically, the decoction volume is equal to the desired change in temperature multiplied by the quantity of the total grain weight multiplied by its heat content (.4) plus twice the initial water volume, divided by the quantity of the difference in temperature between the decoction and the initial temperature of the mash multiplied by the quantity of the decoction grain weight multiplied by its heat content (.4) plus twice the decoction water volume. In other words, the decoction volume is equal to the ratio of the heat content of the two masses.

How many liters of oxygen for how long to achieve 10 ppm in the wort? That is a difficult question because there are so many factors. The only definitive answer is to measure it with a dissolved oxygen meter as you are adding it. The variables are: the oxygen flow rate (the quantity being presented to the wort), the wort temperature (controls the solubility of oxygen in the wort), the size of the bubbles from the diffusion stone (the contact area for diffusion/solubility), the depth of the stone in the wort (the contact time as the bubble rises to the surface) and the wort volume. The combination of all those factors against the amount of wort you are trying to fill with oxygen will determine how long it will take to achieve 10 ppm. There is a very good discussion of wort oxygenation in the new book Yeast, by Chris White and Jamil Zainasheff. To make a long story short, a 1-2 minute flow from one of those Bernz-0-matic oxygen cylinders thru a typical 0.5 micron airstone should achieve 10-14 ppm in 5 gallons of wort that is less than 75°F.

Bruce from Washington asks:Question 1 - On your residual alkalinity spreadsheet, you designate water profiles as appropriate to malty, balanced, and bitter styles based on chloride to sulfate ratio. What is the background for that? Intuitively it seems reasonable, but I have not seen it mentioned in many other books I have read.

Question 2 - My system includes a stainless kettle that I use to boil and heat hot liquor, and a round beverage cooler mash / lauter tun with a false bottom. After mash conversion, and before I batch sparge, I need to get the sparge water out of my boil kettle. I transfer it to a second cooler. But I usually heat my sparge water to 180F or higher. On a Sunday Session from way back, Chris Graham mentioned that the coolers are only food grade to a temperature somewhere in the 150F range. Would you be concerned about holding 180F sparge water in a plastic cooler?

Palmer answers:The chloride to sulfate ratio is mentioned in several brewing texts but it is not something that gets a lot of attention or description. Generally when it is mentioned, the author states that effect of the ratio is independent of the actual concentrations, and that the effect is limited to a 2:1 or 1:2 type balance. This should be taken with a grain of salt I think. Colin Kaminski of Downtown Joe’s and I are working on the water book for the Brewing Elements Series from Brewers Publications, and he has conducted lots of experiments on this effect. His data shows that Sulfate to Chloride ratios of up to 9:1 have positive effects on hoppy beers, but a Chloride to Sulfate ratio of 2:1 is about as high as you want to get before the beer flavor starts being adversely affected. We will work to define the effect better in the book.

The term “Food Grade” is commonly used but does not have a fixed definition – much like the term “edible” does not necessarily mean “non-toxic”. Being a metallurgist, I don’t have a strong grasp of organic chemistry and suggest we find an organic chemist on the forums and ask them this question. That being said, here is my advice for using plastics with hot water: If you can smell plastic, chances are that it is not good for the flavor of your beer, and two, hot plastic tends to behave plastically, and deforms. Depending on the plastics used in the cooler, the health risks may be minimal, but the physical risks from thermo-mechanical failure may be high.

Palmer answers:Alas, I have not brewed with Sorghum malt extract. From what I understand it has an earthier, grainier flavor than barley, and has some tannic bitterness as well. It probably needs less IBUs per recipe than a barley malt extract recipe would for the same style. Looking at your recipe, I do notice two problems – the flaked corn and the flaked rice. These are starch adjuncts and need enzymes for conversion. They need to be mashed with barley malt or enzymes to convert the starches to fermentable sugars. You could use malted sorghum and its enzymes, but there is a catch – sorghum’s gelatinization temperature is above the denaturing temperature for the alpha and beta amylase, so a special cereal/decoction mash is called for if you are going to make an all-grain brew with sorghum. The sorghum malt extract does not require mashing of course, but you will not get any utilization from the rice or corn without it, and you will not get any utilization from the rice or corn without it, and you will not get much flavor from steeping them.

Paul from Texas asks:Read your book (the actual paperback) and it is a fantastic reference now. My question is this: I am a big fan of bold Belgian beers and trying new techniques. I am considering trying an open fermentation for an up and coming brew and want to know about the so called CO2 covering the beer? I have read that it doesn't keep bugs out and others say it is a fantastic repellent since it is heavier than oxygen and bugs can't breath. I feel like the latter is more likely since this was the process before people started using closed vessels. Any help is much appreciated.

Palmer answers:Do open fermentations naturally repel insects? Or do they die and fall in during their reconnaissance? I don’t know, but several of my friends that routinely practice open fermentations actually practice “covered” open fermentations, using a pot lid to keep out dust and other airborne debris during the ferment. I would recommend that you at least use aluminum foil to tent the top of the fermentor with the edges overhanging the sides to prevent critters from fowling the brew. If there is several inches of freeboard above the fermentation, the CO2 will form a blanket but it does not keep oxygen out of the krausen, in fact, that is why the yeast form a krausen on top - better access to the oxygen to catalyze regeneration. After the krausen falls, you will want to transfer the beer to a closed fermentor for conditioning and to prevent oxidation of the beer. Check out Wild Brews by Jeff Sparrow, Farmhouse Ales by Phil Markowski, and Brew Like a Monk by Stan Hieronymus for more insight into brewing Belgian styles.

Nathaniel from California asks:I recently read that the sugar composition of wort (i.e. percentage maltose, sucrose, etc.) has an effect on the fermentation profile of the resulting beer. The extent of it was that more esters are produced from glucose metabolism than are from maltose metabolism. What I'm wondering is, how do the other sugars present in wort affect the fermentation profile? Is it all simply related to ester formation, or are other compounds at play? And are there any practical methods of controlling the concentrations of different sugars present in the raw wort?

Palmer answers:I think I read the same article, by Graham Stewart? Studies on the "Uptake and Metabolism of Wort Sugars During Brewing Fermentations", MBAA TQ, Vol 43, no. 4, 2006? Your question on what other sugars or compounds play a significant role in ester formation and beer flavor is a good one, but a bit beyond my expertise. I will have to wait for the next issue of the Technical Quarterly and see what’s what. But on the other hand, I can lay out a few basic facts which can place some boundaries around the unknown answer. First, brewer’s yeast only ferment a few sugars – glucose, fructose, galactose, and mannose (all monosaccharides), maltose and sucrose (disaccharides) and maltotriose (trisaccharide). There is one other, a tetrasaccharide called maltotetraose, but not much is known about the fermentation of that sugar and it occurs at low concentrations. As you have learned, worts high in sucrose, glucose or fructose tend to produce a lot of esters, versus worts of the same gravity having a higher proportion of maltose. I have not read anything on worts with a higher proportion of maltotriose than maltose. My point is that there are not a lot of mystery sugars waiting in the wings that yeast can secretly utilize to create new flavors.

Third, a typical wort consists of mostly maltose, then maltotriose, then sucrose, glucose and fructose in descending order. Yeast that have been grown from maltose-rich worts have higher viability and vitality than yeast raised on glucose.

Fourth, while there are several theories on why yeast create esters, a leading theory is that yeast create more esters when they are under stress. Yeast do not have to expend energy to metabolize glucose and fructose, but they do have to work to take in maltose and maltotriose. Therefore I am conjecturing that glucose and fructose represent junk food to the yeast, whereas maltose and maltotriose are meat and potatoes. The addition of some junk food to the fermentation can make for a non-typical result and some interesting esters. Too much junk food to the yeast ends up not tasting like beer.

Finally, beer flavor comes from more than just esters, and one primary example are melanoidins that come from the malts and boil. Melanoidins are a chemical combination of a protein and a sugar. And this is where other sugars can play a big role in beer flavor. These Maillard reaction compounds can produce a wide variety of flavors and aromas that can smell like fruity esters, or vanilla, chocolate, or coffee.